Gypsum panels, systems, and methods

ABSTRACT

Gypsum panels and methods of making gypsum panels are provided. Methods of making gypsum panels include: depositing a first gypsum slurry onto a first surface of a first fiberglass mat; allowing the first gypsum slurry to set to form at least a portion of a gypsum core; and applying a substantially continuous barrier coating comprising a polymer binder to a second surface, opposite the first surface, of the first fiberglass mat, in an amount of from about 1 lb/MSF to about 40 lb/MSF, such that the substantially continuous barrier coating has an average thickness of from about 1 micron to about 100 microns, wherein the substantially continuous barrier coating eliminates at least 99 percent of pin holes present in the exposed second surface of the first fiberglass mat.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of Ser. No. 16/770,489filed on Jun. 5, 2020 which claims priority to PCT Application No.PCT/US18/64626, filed on Dec. 7, 2018, which further claims priority toU.S. Provisional Application No. 62/596,236, filed on Dec. 8, 2017,which are incorporated by reference herein in their entireties.

BACKGROUND

The present invention relates generally to the field of panels for usein building construction, and more particularly to gypsum panels andmethods of making gypsum panels.

Typical building panels, or building sheathing, include a core material,such as gypsum, and a mat facer, such as a fiberglass mat facer. Duringmanufacturing, the gypsum core material is traditionally applied as aslurry to a surface of the mat facer and allowed to set, such that themat facer and gypsum core are adhered at the interface. Often, suchpanels suffer from water intrusion and other performance issues.

For example, poor slurry infiltration at the mat facer may lead toincreased porosity of the panel, resulting in increased waterpenetration and decreased weathering performance. Thus, such panels maynot meet building code requirements for air and water penetration.Indeed, many modern building codes require the use of barriers inconstruction to protect the building from air and water penetration. Forexample, building codes in eastern Canada and the northeastern UnitedStates now require air barriers to be used in all construction.Moreover, the existing International Building Code/InternationalResidential Code (IBC/IRC) requires the use of a water resistive airbarrier for all new construction. Common water-resistive air barriersare formed from a variety of materials and structures and applied to thesurface of sheathing panels (e.g., gypsum panels, oriented strand boardpanels).

Traditionally, three types of water resistive air barriers may be usedto meet building codes. First, fabric type membranes, or “wraps,” may beused to cover the surface of building sheathing panels. However, thesefabric wraps are typically unable to withstand wind conditions, sufferfrom drooping, and are difficult to install at heights. Moreover, thestandard method of attaching such fabric membranes to sheathing panelsis stapling, which compromises the effectiveness of the membrane as anair or water barrier. Second, a liquid coating water resistive airbarrier membrane may be applied to sheathing panels. However, theseliquid coatings must be applied in the field by qualified contractors,which is time intensive and costly. Moreover, although liquid coatingsserve as effective an water barrier, they provide low water vaporpermeance, which affects the wall's ability to dry should it get wetduring service (e.g., around window penetrations, flashing). Third,self-adhered, or “peel and stick,” water resistive air barrier membranesmay be applied to sheathing panels. However, these self-adheredmembranes are generally not permeable and therefore are not an option inmany projects, because the architect or engineer must account for thisimpermeability in designing the building, to prevent the potential formoisture being trapped inside the wall cavity. Furthermore, self-adheredmembranes require the sheathing panels to be dry and often primed priorto application, which significantly slows down the construction process.

Accordingly, it would be desirable to provide panels having improvedwater-resistive properties.

SUMMARY

In one aspect, methods of making a gypsum panel are provided, including:depositing a first gypsum slurry onto a first surface of a firstfiberglass mat; allowing the first gypsum slurry to set to form at leasta portion of a gypsum core; and applying a substantially continuousbarrier coating comprising a polymer binder to a second surface,opposite the first surface, of the first fiberglass mat, in an amount offrom about 1 lb/MSF to about 40 lb/MSF, such that the substantiallycontinuous barrier coating has an average thickness of from about 1micron to about 100 microns, wherein the substantially continuousbarrier coating eliminates at least 99 percent of pin holes present inthe exposed second surface of the first fiberglass mat.

In another aspect, gypsum panels are provided, including a set gypsumcore associated with a first surface of a first fiberglass mat; and asubstantially continuous barrier coating comprising a polymer binderapplied to a second surface, opposite the first surface, of the firstfiberglass mat, in an amount of from about 1 lb/MSF to about 40 lb/MSF,such that the substantially continuous barrier coating has an averagethickness of from about 1 micron to about 100 microns, wherein thesubstantially continuous barrier coating eliminates at least 99 percentof pin holes present in the exposed second surface of the firstfiberglass mat.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, which are meant to be exemplary and notlimiting, and wherein like elements are numbered alike. The detaileddescription is set forth with reference to the accompanying drawingsillustrating examples of the disclosure, in which use of the samereference numerals indicates similar or identical items. Certainembodiments of the present disclosure may include elements, components,and/or configurations other than those illustrated in the drawings, andsome of the elements, components, and/or configurations illustrated inthe drawings may not be present in certain embodiments.

FIG. 1 is a cross-sectional view of a fiberglass faced gypsum panelhaving a thin substantially continuous barrier coating.

FIG. 2 is a cross-sectional view of a fiberglass faced gypsum panelhaving a thin substantially continuous barrier coating.

FIG. 3 is a cross-sectional view of a fiberglass faced gypsum panelhaving a thin substantially continuous barrier coating.

FIG. 4 is a perspective view of a building sheathing system.

FIG. 5A is a side view of an experimental apparatus used for thehydrostatic head tests of the Examples.

FIG. 5B is a top view of an experimental apparatus used for thehydrostatic head tests of the Examples.

FIG. 6 is a graph of percent weight gain of various sample boards testedin the Examples.

FIG. 7 is a graph of water column loss of various sampled boards testedin the Examples.

FIG. 8 is a micrograph of an uncoated comparative board tested in theExamples.

FIG. 9 is a micrograph of coated board sample tested in the Examples.

DETAILED DESCRIPTION

Improved water repelling, or water-resistive, gypsum panels have beendeveloped, along with associated methods for their manufacture. Incertain embodiments, the panels have a substantially continuous, thinfilm coating applied to an external surface of a mat facer of the panel.These panels provide advantages over commercially available gypsumpanels. For example, such panels beneficially may enhance the buildingproduct performance characteristics such as water repellence, moisturemigration, fire resistance, IR reflectivity, conductivity, UVresistance, freeze thaw durability, and other weather relatedproperties. As a protective barrier, the thin film coating may reducesurface abrasion, dusting, abrasiveness, or itchiness from the panelfacing materials. As a water-resistive barrier, the coating may resistwater penetration under certain hydrostatic pressure.

As used herein, the term “water-resistive barrier” refers to the abilityof a panel or system to resist liquid bulk water from penetrating,leaking, or seeping past the sheathing and into the surrounding wallcomponents while also providing a water vapor transmission rate, orpermeance, that is high enough to allow any moisture that does developin the wall to dry. Combined with flashing around openings, suchwater-resistive barriers may create a shingled effect to direct wateraway from the sheathing and surrounding wall components. As used herein,the term “air barrier” refers to the ability of a panel or system toresist the movement of air into (infiltration) and out of (exfiltration)conditioned spaces, to create a more energy efficient structure. As usedherein, the term “water-resistive air barrier” refers to the ability ofa panel or system to display both water-resistive barrier and airbarrier properties.

Gypsum sheathing panels or boards may contain a set gypsum coresandwiched between two fibrous glass mats, one or both of which may becoated. The coating may be a substantially continuous barrier coating.As used herein, the term “substantially continuous barrier coating”refers to a coating material that is substantially uninterrupted overthe surface of the fibrous mat.

During manufacturing, a gypsum slurry may be deposited on the uncoatedsurface of the fiberglass mat and set to form a gypsum core of thepanel. The gypsum slurry may penetrate some portion of the thickness ofthe fiberglass mat and provide a mechanical bond for the panel. Thegypsum slurry may be provided in one or more layers, having the same ordifferent compositions, including one or more slate coat layers. As usedherein, the term “slate coat” refers to a gypsum slurry having a higherwet density than the remainder of the gypsum slurry that forms thegypsum core.

Traditional gypsum sheathing panels do not consistently pass industrystandard bulk water holdout tests and therefore are typically coveredwith commercially available water-resistive air barriers (e.g.,mechanically attached flexible sheets, self-adhered sheets,fluid-applied membranes or coatings, sprayed foams). It has beendetermined that water leaks in these traditional sheathing panels areformed not only because the seams and openings are not treated, but alsobecause water under pressure is able to penetrate though pin holes inthe coating on the fiberglass mat surface and travel through the glassmat along small air pockets or channels underneath the coating and alongthe top of the set gypsum core. This phenomenon is especially noteworthyat or near the edges of the gypsum panel, where open pockets at thegypsum core-glass mat interface are more numerous and voluminous. Theseair pockets, if interconnected, allow water to travel under the glassmat coating, resulting in leaks under treated seams, openings, andfasteners.

As such, the present disclosure is directed to providing gypsum panelsand sheathing systems in which such pin holes in the coating on thefiberglass mat are substantially eliminated, so that the panels displaythe desired water resistive barrier and air barrier propertiesindependent of externally applied barrier products. Such improvedsheathing panels may be combined with seaming components (i.e.,components that treat the joints, or seams, between panels) to greatlyreduce the cost, time, and complexity of installation of awater-resistive air barrier that provides the desired resistance to bulkwater.

While this disclosure is generally directed to gypsum panels, it shouldbe understood that other cementitious panel core materials are alsointended to fall within the scope of the present disclosure. Forexample, cementitious panel core materials such as those includingmagnesium oxide or aluminosilicate may be substituted for the gypsum ofthe embodiments disclosed herein, to achieve similar results.

Moreover, while embodiments of the present disclosure are describedgenerally with reference to fiberglass mats, it should be understoodthat other mat materials, including other fibrous mat materials, mayalso be used in the present panels. In certain embodiments, the nonwovenfibrous mat is formed of fiber material that is capable of forming astrong bond with the material of the building panel core through amechanical-like interlocking between the interstices of the fibrous matand portions of the core material. Examples of fiber materials for usein the nonwoven mats include mineral-type materials such as glassfibers, synthetic resin fibers, and mixtures or blends thereof. Bothchopped strands and continuous strands may be used.

Various embodiments of this disclosure are for purposes of illustrationonly. Parameters of different steps, components, and features of theembodiments are described separately, but may be combined consistentlywith this description of claims, to enable other embodiments as well tobe understood by those skilled in the art. Various terms used herein arelikewise defined in the description, which follows.

Panels and Systems

In certain embodiments, as shown in FIG. 1 , a gypsum panel 100 includesa gypsum core 101 having a first surface and a second opposed surface,and a first fiberglass mat 104 associated with the first surface of thegypsum core 101, such that gypsum of the gypsum core penetrates at leasta portion of the first fiberglass mat 104. The various layers areillustrated as separate layers in the figures for ease of illustration;however, it should be understood that overlap of these materials mayoccur at their interfaces.

In certain embodiments, the gypsum panel 100 includes a set gypsum core101 associated with a first surface of first fiberglass mat 104 and asubstantially continuous barrier coating 106 containing a polymer binderapplied to a second surface of the first fiberglass mat 104. Thesubstantially continuous barrier coating 106 eliminates at least 99percent of pin holes present in the exposed second surface (i.e.,exposed prior to application of the coating thereto) of the firstfiberglass mat 104. The substantially continuous barrier coating 106 maybe significantly thinner than traditional panel coatings. In someembodiments, the substantially continuous barrier coating 106 has anaverage thickness of from about 1 micron to about 100 microns, such asfrom about 1 micron to about 50 microns. In some embodiments, thecoating material forming the substantially continuous barrier coating106 is applied to the fiberglass mat 104 in an amount of from about 1lb/MSF to about 40 lb/MSF, such as from about 1 lb/MSF to about 25lb/MSF, or from about 10 lb/MSF to about 15 lb/MSF.

It has been discovered that the particular coating materials describedherein beneficially form a continuous, durable, functional thin film onthe surface of building material panels that enhance the buildingproduct performance characteristics such as water repellence, moisturemigration, fire resistance, IR reflectivity, conductivity, UVresistance, freeze thaw durability, and other weather relatedproperties. As a protective barrier, the thin film coating may reducesurface abrasion, dusting, abrasiveness, or itchiness from the panelfacing materials. As a water barrier, the coating may resist waterpenetration under certain hydrostatic pressures.

The substantially continuous barrier coating may have a dry weight offrom about 1 pound to about 25 pounds, per thousand square feet of boardsurface, such as less than 15 pounds per thousand square feet. Asdiscussed above, the thin film coating may be substantially continuous,such that it covers at least 99 percent of the board surface, or atleast 99.9 percent of the board surface.

Suitable coating materials (i.e., the precursor to the driedsubstantially continuous barrier coating) contain at least one suitablepolymer binder. Suitable polymer binders may be selected from polymericemulsions and resins, e.g. acrylics, siloxane, silicone,styrene-butadiene copolymers, polyethylene-vinyl acetate, polyvinylalcohol, polyvinyl chloride (PVC), polyurethane, urea-formaldehyderesin, phenolics resin, polyvinyl butyryl, styrene-acrylic copolymers,styrene-vinyl-acrylic copolymers, styrene-maleic anhydride copolymers,alkyd emulsions. In some embodiments, the polymer binder is an acryliclatex or a polystyrene latex. For example, the polymer binder mayinclude an ultra-small particle size or structured nano acrylic latex ora polystyrene-acrylic copolymer latex. As used herein, the term“ultra-small particle size refers to particle sizes in the range of fromabout 20 nm to about 200 nm. As used herein, the term “structured nano”refers to two- and three-dimensionally structured nanoparticles.

In some embodiments, the polymer binder is hydrophobic. In certainembodiments, the binder includes UV curable monomers and/or polymers(e.g. epoxy acrylate, urethane acrylate, polyester acrylate). In certainembodiments, the substantially continuous barrier coating contains thepolymer binder in an amount of from about 5 percent to about 75 percent,by weight, on a dry basis.

Examples of suitable polymer binders that may be used in the continuousbarrier coatings described herein include SNAP 720, commerciallyavailable from Arkema Coating Resins, which is a structurednano-particle acrylic polymer containing 100% acrylic latex and 49%solids by weight, with a 0.08 micron particle size; SNAP 728,commercially available from Arkema Coating Resins, which is a structurednano-acrylic polymer containing 100% acrylic latex and 49% solids byweight, with a 0.1 micron particle size; and NEOCAR 820, commerciallyavailable from Arkema Coating Reins, which is a hydrophobic modifiedacrylic latex containing 45% solids by weight, with a 0.07 micronparticle size.

In certain embodiments, the substantially continuous barrier coatingalso contains one or more inorganic fillers. For example, the inorganicfiller may be calcium carbonate or another suitable filler known in theindustry. In certain embodiments, the filler is an inorganic mineralfiller, such as ground limestone (calcium carbonate), clay, mica, gypsum(calcium sulfate dihydrate), aluminum trihydrate (ATH), antimony oxide,sodium-potassium alumina silicates, pyrophyllite, microcrystallinesilica, and talc (magnesium silicate). In certain embodiments, thefiller may inherently contain a naturally occurring inorganic adhesivebinder. For example, the filler may be limestone containing quicklime(CaO), clay containing calcium silicate, sand containing calciumsilicate, aluminum trihydrate containing aluminum hydroxide,cementitious fly ash, or magnesium oxide containing either the sulfateor chloride of magnesium, or both. In certain embodiments, the fillermay include an inorganic adhesive binder as a constituent, cure byhydration, and act as a flame suppressant. For example, the filler maybe aluminum trihydrate (ATH), calcium sulfate (gypsum), and theoxychloride and oxysulfate of magnesium. For example, fillers mayinclude MINEX 7, commercially available from the Cary Company (Addison,IL); IMSIL A-10, commercially available from the Cary Company; andTALCRON MP 44-26, commercially available from Specialty Minerals Inc.(Dillon, MT). The filler may be in a particulate form. For example, thefiller may have a particle size such that at least 95% of the particlespass through a 100 mesh wire screen.

In certain embodiments, the precursor material that forms thesubstantially continuous barrier coating also contains water. Forexample, the coating material may contain the polymer binder in anamount of from about 35 percent to about 80 percent, by weight, andwater in an amount of from about 20 percent to about 65 percent, byweight. For example, the coating material may contain the polymer binderin an amount of from about 70 percent to about 80 percent, by weight,and water in an amount of from about 20 percent to about 30 percent, byweight. In embodiments containing the filler, the continuous barriercoating material may also contain an inorganic filler in an amount offrom about 35 percent to about 80 percent, by weight. In suchembodiments containing the inorganic filler, the continuous barriercoating may contain the polymer binder in an amount of from about 10percent to about 40 percent, by weight, and water in an amount of fromabout 10 percent to about 40 percent, by weight. In some embodiments,the polymer binder and the inorganic filler are present in amounts ofwithin 5 percent, by weight, of each other. For example, the polymerbinder and filler may be present in a ratio of approximately 1:1.

In some embodiments, additional additives or other ingredients are alsoincluded for the thin film functionality. In certain embodiments, thecontinuous barrier coating also includes water and/or other optionalingredients such as colorants (e.g., dyes or pigments), transfer agents,thickeners or rheological control agents, surfactants, ammoniacompositions, defoamers, dispersants, biocides, UV absorbers, andpreservatives. Thickeners may include hydroxyethyl cellulose;hydrophobically modified ethylene oxide urethane; processed attapulgite,a hydrated magnesium aluminosilicate; and other thickeners known tothose of ordinary skill in the art. For example, thickeners may includeCELLOSIZE QP-09-L and ACRYSOL RM-2020NPR, commercially available fromDow Chemical Company (Philadelphia, PA); and ATTAGEL 50, commerciallyavailable from BASF Corporation (Florham Park, NJ). Surfactants mayinclude sodium polyacrylate dispersants, ethoxylated nonionic compounds,and other surfactants known to those of ordinary skill in the art. Forexample, surfactants may include HYDROPALAT 44, commercially availablefrom BASF Corporation; and DYNOL 607, commercially available from AirProducts (Allentown, PA). Defoamers may include multi-hydrophobe blenddefoamers and other defoamers known to those of ordinary skill in theart. For example, defoamers may include FOAMASTER SA-3, commerciallyavailable from BASF Corporation. Ammonia compositions may includeammonium hydroxide, for example, AQUA AMMONIA 26 BE, commerciallyavailable from Tanner Industries, Inc. (Southampton, PA). Biocides mayinclude broad-spectrum microbicides that prohibit bacteria and fungigrowth, antimicrobials such as those based on the activediiodomethyl-ptolylsulfone, and other compounds known to those ofordinary skill in the art. For example, biocides may include KATHON LX1.5%, commercially available from Dow Chemical Company, POLYPHASE 663,commercially available from Troy Corporation (Newark, NJ), and AMICALFlowable, commercially available from Dow Chemical Company. Biocides mayalso act as preservatives. UV absorbers may include encapsulatedhydroxyphenyl-triazine compositions and other compounds known to thoseof ordinary skill in the art, for example, TINUVIN 477DW, commerciallyavailable from BASF Corporation. Transfer agents such as polyvinylalcohol (PVA) and other compounds known to those of ordinary skill inthe art may also be included in the coating composition.

In certain embodiments, as will be described in greater detail in theExamples below, the substantially continuous barrier material coatinghas a viscosity (at the time of application to the mat) of from about 30cps to about 1,000 cps. For example, the viscosity may be from about 80cps to about 800 cps. For example, the viscosity may be from about 700cps to about 1,000 cps.

In certain embodiments, the substantially continuous barrier coatingmaterial has a pH of from about 5 to about 12, such as from about 6.5 toabout 9. It has been determined that such coating materialsadvantageously are able to provide an ultra-thin, yet continuous coatingthat provides the desired water resistance and air barrier propertiesfor the building panel.

In some embodiments, as shown in FIG. 1 , the gypsum of the gypsum core101 penetrates a remaining portion of the first fiberglass mat 104 suchthat voids in the first fiberglass mat 104 are substantially eliminatedand the water resistance of the panel 100 is further enhanced. Forexample, in one embodiment, the first fiberglass mat 104 has asubstantially continuous barrier material coating 106 on a surfaceopposite the gypsum core 101, the substantially continuous barriermaterial coating 106 penetrating a portion of the first fiberglass mat104, to define the remaining portion of the first fiberglass mat 104.That is, gypsum of the gypsum core 101 may penetrate a remaining fibrousportion of the first fiberglass mat 104 such that voids in the firstfiberglass mat 104 are substantially eliminated.

As used herein the phrase “such that voids in the fiberglass mat aresubstantially eliminated” and similar phrases, refer to the gypsumslurry, and thus the set gypsum, of the gypsum core filling all ornearly all of the interstitial volume of the fiberglass mat that is notfilled by the coating material. In certain embodiments, the gypsum ofthe gypsum core fills at least 95 percent of the available interstitialvolume of the coated fiberglass mat. In some embodiments, the gypsumcore fills at least 98 percent of the available interstitial volume ofthe coated fiberglass mat. In further embodiments, the gypsum core fillsat least 99 percent of the available interstitial volume of the coatedfiberglass mat. Such panels, in which the gypsum penetrates the mat suchthat the voids in the mat are substantially eliminated, may bemanufactured via a variety of methods, as discussed in more detailherein. For example, the gypsum that contacts the non-coated surface ofthe fiberglass mat may be hydrophobic or otherwise chemically modifiedfor improved mat penetration, and/or mechanical means may be used toenhance penetration of the gypsum slurry into the mat.

By maximizing gypsum slurry penetration into the side of the fiberglassmat receiving gypsum, the movement of water under the mat coating withinthe glass mat of the finished panel when exposed to bulk water headpressures may be substantially and adequately reduced, withoutsignificantly altering the water vapor transmission rate (i.e., theability to dry) of the finished panel. Thus, the gypsum panels disclosedherein may have one or more improved water-resistive barrier properties.

In certain embodiments, the mat 104 is a nonwoven fiberglass mat. Forexample, the glass fibers may have an average diameter of from about 10to about 17 microns and an average length of from about ¼ inch to about1 inch. For example, the glass fibers may have an average diameter of 13microns (i.e., K fibers) and an average length of ¾ inch. In certainembodiments, the non-woven fiberglass mats have a basis weight of fromabout 1.5 pounds to about 3.5 pounds per 100 square feet of the mat. Themats may each have a thickness of from about 20 mils to about 35 mils.The fibers may be bonded together to form a unitary mat structure by asuitable adhesive. For example, the adhesive may be a urea-formaldehyderesin adhesive, optionally modified with a thermoplastic extender orcross-linker, such as an acrylic cross-linker, or an acrylate adhesiveresin.

In certain embodiments, as shown in FIG. 1 , the gypsum core 101includes two or more gypsum layers 102, 108. For example, the gypsumcore may include various gypsum layers having different compositions. Insome embodiments, the first gypsum layer 102 that is in contact with thefiberglass mat 104 (i.e., the layer that forms an interface with thecoating material 106 and at least partially penetrates the remainingfibrous portion of the first fiberglass mat) is a slate coat layer. Insome embodiments, the first gypsum layer 102 is present in an amountfrom about 5 percent to about 20 percent, by weight, of the gypsum core101. The various gypsum layers are shown as separate layers in thefigures for ease of illustration; however, it should be understood thatoverlap of these materials may occur at their interfaces.

In some embodiments, the slurry that forms the gypsum layer having aninterface with the barrier coating includes a wetting agent tofacilitate penetration of the slurry into the fibrous mat. This slurrymay form the entire gypsum core or may form one or more layers of thegypsum core. That is, one or more layers forming the gypsum core maycontain the wetting agent. As discussed in more detail below, thewetting agent may be any agent that reduces the surface tension of theslurry. In certain embodiments, the first gypsum layer includes awetting agent in an amount effective to bring a slurry surface tensionof the first gypsum layer to 65 dyne/cm or less. In certain embodiments,the first gypsum layer includes a wetting agent in an amount effectiveto bring a slurry surface tension of the first gypsum layer to 60dyne/cm or less. In certain embodiments, the first gypsum layer includesa wetting agent in an amount effective to bring a slurry surface tensionof the first gypsum layer to 55 dyne/cm or less. In certain embodiments,the first gypsum layer includes a wetting agent in an amount effectiveto bring a slurry surface tension of the first gypsum layer to fromabout 30 dyne/cm to about 60 dyne/cm. In certain embodiments, the firstgypsum layer includes a wetting agent in an amount effective to bring aslurry surface tension of the first gypsum layer to from about 40dyne/cm to about 60 dyne/cm. In certain embodiments, the first gypsumlayer includes a polymer binder or an inorganic binder in an amount offrom about 0.5 lb/1000 ft² to about 50 lb/1000 ft², in the set gypsumlayer. In certain embodiments, the first gypsum layer includes a polymerbinder or an inorganic binder in an amount of from about 0.5 lb/1000 ft²to about 15 lb/1000 ft², in the set gypsum layer. In some embodiments,the first gypsum layer has a wet density of from about 88 pcf to about98 pcf. In some embodiments, the first gypsum layer has a wet density offrom about 93 pcf to about 96 pcf.

In certain embodiments, as shown in FIG. 2 , penetration of the gypsumslurry into the fibrous mat is encouraged with a polymer binder coatingor an inorganic binder coating 109 on a surface of the first fiberglassmat 104 that contacts the gypsum core 101. In some embodiments, the matcoating comprises a wetting agent in an amount effective to bring a wetsurface tension of the coating to 60 dyne/cm or less. In someembodiments, the mat coating comprises a wetting agent in an amounteffective to bring a wet surface tension of the coating to from about 30dyne/cm to about 60 dyne/cm. In some embodiments, the mat coatingcomprises a wetting agent in an amount effective to bring a wet surfacetension of the coating to from about 40 dyne/cm to about 60 dyne/cm.

In certain embodiments, as shown in FIG. 3 , a gypsum panel 200 includestwo fiberglass mats 204, 212 that are associated with the gypsum core201. The second fiberglass mat 212 is present on a face of the gypsumcore 201 opposite the first fiberglass mat 204. In some embodiments,only the first fiberglass mat 204 has a substantially continuous barriercoating 206 on a surface thereof. In other embodiments, both fiberglassmats 204, 212 have a coating 206, 214 on a surface thereof opposite thegypsum core 201. In some embodiments, the gypsum core 201 includes threegypsum layers 202, 208, 210. One or both of the gypsum layers 202, 210that are in contact with the fiberglass mats 204, 212 may be a slatecoat layer. In certain embodiments, one or both of the gypsum layers202, 210 that are in contact with the fiberglass mats 204, 212 may be aslate coat layer with hydrophobic characteristics and/or a wet densityof from about 88 pcf to about 98 pcf, or of from about 93 pcf to about96 pcf.

The layers of the gypsum core may be similar to gypsum cores used inother gypsum products, such as gypsum wallboard, dry wall, gypsum board,gypsum lath, and gypsum sheathing. For example, the gypsum core may beformed by mixing water with powdered anhydrous calcium sulfate orcalcium sulfate hemihydrate, also known as calcined gypsum, to form anaqueous gypsum slurry, and thereafter allowing the slurry mixture tohydrate or set into calcium sulfate dihydrate, a relatively hardmaterial. In certain embodiments, the gypsum core includes about 80weight percent or above of set gypsum (i.e., fully hydrated calciumsulfate). For example, the gypsum core may include about 85 weightpercent set gypsum. In some embodiments, the gypsum core includes about95 weight percent set gypsum. The gypsum core may also include a varietyof additives, such as accelerators, set retarders, foaming agents, anddispersing agents.

In certain embodiments, one or more layers of the gypsum core alsoinclude reinforcing fibers, such as chopped glass fibers. For example,the gypsum core, or any layer(s) thereof, may include up to about 0.6pounds of reinforcing fibers per 100 square feet of panel. For example,the gypsum core, or a layer thereof, may include about 0.3 pounds ofreinforcing fibers per 100 square feet of panel. The reinforcing fibersmay have a diameter between about 10 and about 17 microns and have alength between about 6.35 and about 12.7 millimeters.

The gypsum core, or one or more layers thereof, such as one or moreslate coat layers, may also include an additive that improves thewater-resistant properties of the core. Such additives may include, forexample, poly(vinyl alcohol), optionally including a minor amount ofpoly(vinyl acetate); metallic resinates; wax, asphalt, or mixturesthereof, for example as an emulsion; a mixture of wax and/or asphalt andcornflower and potassium permanganate; water insoluble thermoplasticorganic materials such as petroleum and natural asphalt, coal tar, andthermoplastic synthetic resins such as poly(vinyl acetate), poly(vinylchloride), and a copolymer of vinyl acetate and vinyl chloride, andacrylic resins; a mixture of metal rosin soap, a water soluble alkalineearth metal salt, and residual fuel oil; a mixture of petroleum wax inthe form of an emulsion and either residual fuel oil, pine tar, or coaltar; a mixture of residual fuel oil and rosin; aromatic isocyanates anddiisocyanates; organopolysiloxanes; siliconates; wax emulsions,including paraffin, microcrystalline, polyethylene, and variousco-emulsified wax emulsions; wax asphalt emulsion, each optionally withpotassium sulfate, alkali, or alkaline earth aluminates, and Portlandcement; a wax-asphalt emulsion prepared by adding to a blend of moltenwax and asphalt, an oil-soluble, water-dispersing emulsifying agent, andadmixing the aforementioned with a solution of case including, as adispersing agent, an alkali sulfonate of a polyarylmethylenecondensation product. Mixtures of these water-resistance additives mayalso be employed. For example, a mixture of two or more of: poly(vinylalcohol), siliconates, wax emulsion, and wax-asphalt emulsion of theaforementioned types, may be used to improve the water resistance of thegypsum core, or gypsum slate coat layer(s) thereof.

The gypsum core, or one or more layers thereof, may also include one ormore additives that enhance the inherent fire resistance of the gypsumcore. Such additives may include chopped glass fibers, other inorganicfibers, vermiculite, clay, Portland cement, and other silicates, amongothers.

In certain embodiments, the panels have a thickness from about ¼ inch toabout 1 inch. For example, the panels may have a thickness of from about½ inch to about ⅝ inch.

In certain embodiments, as discussed above, the building panelsdescribed herein may display one or more improved performancecharacteristics such as water repellence, moisture migration, fireresistance, IR reflectivity, conductivity, UV resistance, freeze thawdurability, and other weather related properties. As a protectivebarrier, the thin film coating may reduce surface abrasion, dusting,abrasiveness, or itchiness from the panel facing materials. As awater-resistive barrier, the coating may resist water penetration undercertain hydrostatic pressure. In some embodiments, the building paneldisplays an HIHT passing rate of at least 90 percent, as measuredaccording to AATCC 127-2008 and/or AC 212. In certain embodiments, thebuilding panel displays a column water loss of less than 0.25 inch, asmeasured according to AATCC 127-2008 and/or AC 212. In certainembodiments, the gypsum panel displays a water gain of less than 5percent, such as less than 0.5 percent, as measured according to AATCC127-2008 and/or AC 212.

In particular, it was discovered that exterior gypsum panels tend tohave relatively high water absorption rates even with hydrophobic coatedglass mat as facers. Thus, the presently described panels may provideimproved bulk water holdout to resist water intrusion. Without intendingto be bound by a particular theory, it is believed that the particularthin coating materials described herein eliminate pin holes that occurin traditional coatings, such that improved water resistance isachieved. As will be discussed in the Examples below, the panelsdescribed herein show improved hydrostatic head test results, whilemicrographs reveal elimination of pinholes and reduction of surfacewater absorption.

In certain embodiments, the gypsum panel passes a hydrostatic head testagainst water leakage, as measured by AATCC 127-2008. In addition tohydrostatic head pressure tests, other similar tests can be used toassess bulk water resistance in the range of 0.32 inches water (1.67psf) to 44 inches of water head pressure (228 psf). This may include butis not limited to other water head tests (such as ASTM E2140), waterponding tests, cobb tests (such as ASTM C473, ASTM D 3285, ASTM D 5795,ASTM D7433, ASTM D7281), or a chambered test aided by vacuum or negativepressure differentials. Thus, the gypsum panels described herein maypass any combination of the foregoing tests.

In certain embodiments, the gypsum panel has a water vapor permeance ofat least 10 (inch pound units per ASTM E96 wet cup method), in the fieldof the panel (i.e., not at the edge of the panel). In some embodiments,the gypsum panel has a water vapor permeance of at least (inch poundunits per ASTM E96 wet cup method), in the field of the panel. In someembodiments, the gypsum panel has a water vapor permeance of at least 32(inch pound units per ASTM E96 wet cup method), in the field of thepanel. In certain embodiments, the gypsum panel displays water vaportransmission properties as determined by desiccant methods or by othermethods including high and low relative humidity or dynamic pressurelevels.

In certain embodiments, the gypsum panel displays an air penetrationresistance of 0.02 L/sm² at 75 Pa, or less, when measured according toASTM E2178. In certain embodiments, the gypsum panel displays an airpenetration resistance of 0.02 L/sm² at 300 Pa, or less, when measuredaccording to ASTM E2178.

In certain embodiments, the gypsum panel is fire resistant. In certainembodiments, the gypsum panel is classified as noncombustible whentested in accordance with ASTM E 136 or CAN/ULC S114 and complies withASTM C 1177 requirements for glass mat gypsum substrates designed to beused as exterior or sheathing for water barriers. In particular, a ⅝inch panel may have increased fire resistance over other sheathingsubstrates, such as cellulosic based sheathing. In some embodiments, thegypsum panel has a “Type X” designation, when measured according to ASTME119. The gypsum panels may meet “Type X” designation when tested inaccordance with ASTM E119 fire tests for both generic (Generic systemsin the GA-600 Fire Resistance Design Manual) and proprietary buildingassembly wall designs. ASTM E119 is designed to test the duration forwhich a building assembly can contain a fire and retain structuralintegrity under a controlled fire with a standard time/temperaturescurve. In certain embodiments, the gypsum panel has a level 0 flamespread index and smoke develop index, when measured according to ASTME84. For example, when exposed to surface burning characteristics, perASTM E 84 or CAN/ULC-S102, the flame spread index and smoke developindex for the gypsum panel may be 0.

Building sheathing systems are also provided herein, and include atleast two of the improved water-resistive air barrier gypsum panelsdescribed herein, including any features, or combinations of features,of the panels described herein. For example, the gypsum panels may eachinclude a gypsum core associated with a first fiberglass mat having asubstantially continuous barrier coating.

In certain embodiments, as shown in FIG. 4 , a building sheathing systemincludes at least two gypsum panels 300 and a seaming component 320configured to provide a seam at an interface between at least two of thegypsum panels 300. In certain embodiments, the seaming componentcomprises tape or a bonding material. For example, the seaming componentmay be a tape including solvent acrylic adhesives, a tape having apolyethylene top layer with butyl rubber adhesive, a tape having analuminum foil top layer with butyl rubber adhesive, a tape having anEPDM top layer with butyl rubber adhesive, a tape having a polyethylenetop layer with rubberized asphalt adhesive, or a tape having an aluminumfoil top layer with rubberized asphalt adhesive. For example, theseaming component may be a bonding material such as synthetic stuccoplasters, cement plasters, synthetic acrylics, sand filled acrylics,solvent based acrylics, solvent based butyls, polysulfides,polyurethanes, silicones, silyl modified polymers, water-based latexes,EVA latexes, or acrylic latexes.

Thus, the above-described enhanced panels may be installed with either atape, liquid polymer, or other suitable material, to effectively treatareas of potential water and air intrusion, such as seams, door/windowopenings, penetrations, roof/wall interfaces, and wall/foundationinterfaces. As such, the building sheathing panels, when used incombination with a suitable seaming component, create an effectivewater-resistive and/or air barrier envelope.

Such building sheathing systems may advantageously pass any or allICC-ES tests required for water resistant and air barrier systemperformance. For example, the sheathing systems may pass Sections 4.1,4.2, 4.3, 4.4, 4.7, and/or 4.8 of the ICC-ES Acceptance Criteria forwater-resistive coatings used as water-resistive barriers over exteriorsheathing (ICC Evaluation Service Acceptance Criteria 212), datedFebruary 2015. For example, the sheathing systems may pass Section 4.5of the ICC-ES Acceptance Criteria for water-resistive membranes factorybonded to wood-based structural sheathing, used as water-resistivebarriers (ICC Evaluation Service Acceptance Criteria 310), dated May2008, revised June 2013.

In certain embodiments, the building sheathing system including at leasttwo gypsum panels and a seaming component displays no water leaks whenmeasured according ICC Evaluation Service Acceptance Criteria 212,section 4. This test uses an 8′ by 8′ wall assembly built with multiplegypsum panels and having two vertical joint treatments and onehorizontal joint treatment with seaming component(s) (as described inmore detail herein) and flashing treatment with seaming component(s).The wall is subjected to 10 positive transverse load cycles of ASTME2357 (procedure A), to racking loads of ASTM E72 to obtain a netdeflection of ⅛ inch with hold-downs, and then to restrainedenvironmental conditioning cycles as described in AC 212 section 4.7.3for two weeks. Thus, in some embodiments, the building sheathing systemdisplays no water leaks when measured according to ICC EvaluationService Acceptance Criteria 212, Section 4, after being subjected to thetest methods of ASTM E2357 procedure A, ASTM E72, and restrainedenvironmental conditioning. The cycled wall is then tested in ASTM E 331water penetration with a water spray of at least 8 gallons of water perminute and air pressure differential of 2.86 psf, and resulting in noleaks within the field of the panel or cracking of sheathing or seamingcomponents.

Thus, in some embodiments, the building sheathing system displays nowater leaks when measured according to ASTM E331 wall assembly test atan air pressure of 2.86 psf and/or at an air pressure of 8.58 psf. TheASTM E331 test may be a water spray after a structural test and/or atest including the building transitions, openings, and penetrations. Inaddition to ASTM E 331, other suitable tests may be substituted, such astests using chambers that spray or flood the exposed side of the wall orare rotated to receive bulk water and create a negative air pressuredifferential on the inside cavity in order to expose leaks. This mayinclude but is not limited to ASTM E547, ASTM D5957, AAMA 501, or fieldtesting apparatus such as ASTM E1105. Thus, the building sheathingsystems described herein may pass any combination of the foregoingtests.

In certain embodiments, the building sheathing system displays an airpenetration resistance of 0.02 L/sm² at 75 Pa, or less, when measuredaccording to ASTM E2178. In certain embodiments, the sheathing systemdisplays an air penetration resistance of 0.02 L/sm² at 300 Pa, or less,when measured according to ASTM E2178. In certain embodiments, thebuilding sheathing system displays an exfiltration and infiltration airleakage rate of less than 0.04 cfm/ft² at 1.57 lbs/ft² (75 Pa), whenmeasured according to the ASTM E2357 air barrier assembly test for bothopaque walls and walls with penetration, when 8′ by 8′ walls areprepared using seaming components to seal joints, window openings, ductpenetrations, pipe penetrations, external junction boxes, and masonryties. In some embodiments, the ASTM E2357 wall assemblies, after beingis exposed to Q10>0.20 kPa pressure design value wind loads forsustained, cyclic, and gust loads display an air leakage infiltrationand exfiltration rate of less than 0.04 cfm/ft² at 6.27 lbs/ft² (300Pa). In certain embodiments, the building sheathing system displays anexfiltration and infiltration air leakage rate of less than 0.02 cfm/ft²at 1.57 lbs/ft² (75 Pa), when measured according to the ASTM E2357 airbarrier assembly test for both opaque walls and walls with penetration.In addition to ASTM E 2357, other tests may be used to quantify airleakage in this range, including ASTM E283, ASTM E2319, ASTM E1424, ASTME283, ASTM E1424, or similar test methods. Also, related field testingto test pressure differentials, in this range, such as ASTM E783 orrelated blower door apparatus testing may also be used. Thus, thebuilding sheathing systems described herein may pass any combination ofthe foregoing tests.

In some embodiments, the system passes a hydrostatic head test againstwater leakage, as measured by AATCC 127-2008. In certain embodiments,the building sheathing system passes AATCC hydrostatic head test method127-2008 for a 22-inch head of water (114 psf water pressure) directlyover an interface of at least two gypsum panels and the seamingcomponent, with no leaks after 5 hours. In addition to hydrostatic headpressure, other similar tests can be used to assess bulk waterresistance in the range of 0.32 inches water (1.67 psf) to 44 inches ofwater head pressure (228 psf). This may include but is not limited toother water head tests (such as ASTM E2140), water ponding test, cobbtests (such as ASTM C473, ASTM D 3285, ASTM D 5795, ASTM D7433, ASTMD7281), or a chambered test aided by vacuum or negative pressuredifferentials. Thus, the building sheathing systems described herein maypass any combination of the foregoing tests.

In certain embodiments, the system passes AC310-2008, which testswater-resistive membranes & barriers. In some embodiments, the systempasses AAMA 714 standard for liquid-applied flashing. In certainembodiments, the sheathing system has a water vapor permeance of atleast 10 (inch pound units per ASTM E96 wet cup method). In certainembodiments, the sheathing system has a water vapor permeance of atleast 20 (inch pound units per ASTM E96 wet cup method).

Accordingly, the presently described systems are especially effectivealong the edges of the panel, which are traditionally more susceptibleto leaks when installed in a finished system. Thus, in certainembodiments, the sheathing system (i) passes a hydrostatic head testagainst water leakage, as measured by AATCC 127-2008, (ii) displays nowater leaks when measured according to ICC Evaluation Service AcceptanceCriteria 212, Section 4, after being subjected to the test methods ofASTM E2357 procedure A, ASTM E72, and restrained environmentalconditioning, and/or (iii) displays no water leaks when measuredaccording to ASTM E331 wall assembly test at an air pressure of 2.86psf. Therefore, the sheathing system may display certain levels of waterresistive properties. Additionally, such sheathing systems may furtherdisplay desired water vapor permeance, air penetration resistance, airleakage rate, and fire resistant properties. These sheathing systemstherefore provide a water resistive air barrier in the absence of anyexternally applied barrier product, other than the seaming component.That is, no mechanically attached flexible barrier sheet material,self-adhered barrier sheet material, fluid-applied membranes, spray foammembrane, or other barrier product need be applied to the external fieldof the panels to achieve the water-resistive air barrier properties.

Thus, in certain embodiments, the sheathing system includes panelshaving a gypsum core (one or more layers, optionally including one ormore slate coat layers), a fiberglass mat facer, and a substantiallycontinuous mat coating applied to the fiberglass mat facer during orafter the panel manufacturing process, which panels display thewater-resistive air barrier properties described herein, independent ofany barrier product (e.g., mechanically attached flexible barrier sheetmaterial, self-adhered barrier sheet material, fluid-applied membranes,spray foam membrane) being applied to the external surface of the panelduring building construction.

Methods

Methods of making gypsum panels having water-resistive properties arealso provided. In certain embodiments, methods of making a gypsum panelinclude depositing a gypsum slurry onto a surface of a first fiberglassmat, and allowing the gypsum slurry to set to form a gypsum core. Thesemethods may be used to produce gypsum panels having any of the features,or combinations of features, described herein. For example, enhancedpenetration of the gypsum into the fiberglass mat may be achieved bychemical modification of the gypsum slurry, by application of apenetration-enhancing coating on the surface of the fibrous matcontacted by the gypsum slurry, and/or by mechanical means.

In certain embodiments, methods of making gypsum panels includedepositing a first gypsum slurry onto a first surface of a firstfiberglass mat; allowing the first gypsum slurry to set to form at leasta portion of a gypsum core; applying a substantially continuous barriercoating comprising a polymer binder to a second surface, opposite thefirst surface, of the first fiberglass mat, in an amount of from about 1lb/MSF to about 40 lb/MSF, such that the substantially continuousbarrier coating has an average thickness of from about 1 micron to about100 microns, wherein the substantially continuous barrier coatingeliminates at least 99 percent of pin holes present in the exposedsecond surface of the first fiberglass mat. The substantially continuousbarrier coating may be applied in the form of any of the precursormaterials described above with reference to the panels.

For example, the substantially continuous barrier coating may beproduced by depositing a continuous liquid film on the building materialpanels, followed by drying under heat or curing by chemicals or certaintypes of energy (e.g., UV light, IR radiation, thermal, electron beam).Suitable thin film deposition techniques include roll coating, knifecoating, curtain coating, rod coating, spraying, brushing, dipping,transfer coating, and other techniques known in the industry. Forexample, the coating material may be applied by a low pressure sprayer,bar hydraulic spray nozzles, or air atomized spray. For example, thecoating material may be applied in line during the panel manufacturingprocess (i.e., either pre-panel drying or post via a separate dryer orUV cure).

In some embodiments, the substantially continuous barrier coating isapplied to the second surface of the first fiberglass mat prior tosetting of the first gypsum slurry. In other embodiments, thesubstantially continuous barrier coating is applied to the secondsurface of the first fiberglass mat after setting of the first gypsumslurry. In some embodiments, the method also includes setting thecontinuous barrier coating by heat or curing.

In certain embodiments, the gypsum core includes multiple layers thatare sequentially applied to the fiberglass mat, and allowed to seteither sequentially or simultaneously. In other embodiments, the gypsumcore includes a single layer. In some embodiments, a second fiberglassmat may be deposited onto a surface of the final gypsum slurry layer (orthe sole gypsum slurry layer), to form a dual mat-faced gypsum panel.For example, the second fiberglass mat may include a barrier coating onits surface that penetrates a portion of the mat. The gypsum slurry ormultiple layers thereof may be deposited on the fiberglass mat by anysuitable means, such as roll coating.

In certain embodiments, depositing the gypsum slurry includes depositinga first gypsum slurry having a wet density of from about 88 pcf to about98 pcf onto the surface of a fiberglass mat, the first gypsum slurry. Incertain embodiments, the first gypsum slurry has a wet density of fromabout 93 pcf to about 96 pcf. In some embodiments, the gypsum coreincludes at least three gypsum layers, with the outermost gypsum layersof the gypsum core (i.e., the layers that form an interface with thefiberglass mats) being slate coat layers. In certain embodiments, bothoutermost layers have a relatively high density or are otherwisechemically altered for enhanced penetration. Thus, a third gypsum slurrymay have a wet density of from about 88 pcf to about 98 pcf, or fromabout 93 pcf to about 96 pcf.

In certain embodiments, depositing the gypsum slurry includes depositinga first gypsum slurry containing a wetting agent, as described in moredetail below. The first gypsum slurry may be the first of multiplegypsum layers deposited to form the gypsum core (i.e., a slate coatlayer), or the first gypsum slurry may be the sole gypsum layerdeposited to form the gypsum core. The first gypsum slurry (or both ofthe outermost gypsum slurries) may contain a wetting agent in an amounteffective to reduce a surface tension of the first gypsum slurry to 65dyne/cm or less, measured on the aqueous liquid after solid ingredientsare filtered out. In certain embodiments, the first gypsum slurrycontains a wetting agent in an amount effective to reduce a surfacetension of the first gypsum slurry to 60 dyne/cm or less. In certainembodiments, the first gypsum slurry contains a wetting agent in anamount effective to reduce a surface tension of the first gypsum slurryto 55 dyne/cm or less. In certain embodiments, the first gypsum slurryincludes a wetting agent in an amount effective to reduce a surfacetension of the first gypsum slurry to from about 40 dyne/cm to about 65dyne/cm. The reduced surface tension of aqueous liquid in the gypsumslurry enhances the slurry penetration into the glass mat, in referenceto the pure water surface tension of 72 dyne/cm at 25° C.

In certain embodiments, the first gypsum slurry (or each of theoutermost gypsum slurry layers) is deposited in an amount of from about5 percent to about 20 percent, by weight, of the gypsum core.

In certain embodiments, the wetting agent is selected from a groupconsisting of surfactants, superplasticisers, dispersants, agentscontaining surfactants, agents containing superplasticisers, agentscontaining dispersants, and combinations thereof. For example, thegypsum slurry or layer(s) may include wax, wax emulsions andco-emulsions, silicone, siloxane, or a combination thereof. For example,suitable superplasticisers include Melflux 2651 F and 4930F,commercially available from BASF Corporation. In certain embodiments,the wetting agent is a surfactant having a boiling point of 200° C. orlower. In some embodiments, the surfactant has a boiling point of 150°C. or lower. In some embodiments, the surfactant has a boiling point of110° C. or lower. For example, the surfactant may be a multifunctionalagent based on acetylenic chemistry or an ethoxylated low-foam agent.Without intending to be bound by a particular, it is believed that useof a surfactant having such a low boiling or decomposition temperatureencourages evaporation an thereby loss of wetting functionality duringthe board drying process. In particular, high Cobb (surface waterabsorption) was found in certain boards due to residual surfactants leftin the glass mat on board surface, which promoted wetting again andincreased surface water absorption. Even at higher board dryingtemperatures, the temperature was still not high enough to evaporate offall surfactants, and Cobb remained high. Therefore the low boiling pointsurfactants advantageously demonstrate increased surface evaporation andresulting low Cobb (water absorption) properties. In certainembodiments, there is no residual wetting agent present in the setgypsum core.

In certain embodiments, the surfactant is present in the first gypsumslurry in an amount of about 0.01 percent to about 1 percent, by weight.In certain embodiments, the surfactant is present in the first gypsumslurry in an amount of about 0.01 percent to about 0.5 percent, byweight. In some embodiments, the surfactant is present in the firstgypsum slurry in an amount of about 0.05 percent to about 0.2 percent,by weight.

Suitable surfactants and other wetting agents may be selected fromnon-ionic, anionic, cationic, or zwitterionic compounds, such as alkylsulfates, ammonium lauryl sulfate, sodium lauryl sulfate, alkyl-ethersulfates, sodium laureth sulfate, sodium myreth sulfate, docusates,dioctyl sodium sulfosuccinate, perfluorooctanesulfonate,perfluorobutanesulfonate, linear alkylbenzene sulfonates, alkyl-arylether phosphates, alkyl ether phosphate, alkyl carboxylates, sodiumstearate, sodium lauroyl sarcosinate, carboxylate-basedfluorosurfactants, perfluorononanoate, perfluorooctanoate, amines,octenidine dihydrochloride, alkyltrimethylammonium salts, cetyltrimethylammonium bromide, cetyl trimethylammonium chloride,cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride,5-Bromo-5-nitro-1,3-dioxane, dimethyldioctadecylammonium chloride,cetrimonium bromide, dioctadecyldimethylammonium bromide, sultaines,cocamidopropyl hydroxysultaine, betaines, cocamidopropyl betaine,phospholipids phosphatidylserine, phosphatidylethanolamine,phosphatidylcholine, sphingomyelins, fatty alcohols, cetyl alcohol,stearyl alcohol, cetostearyl alcohol, stearyl alcohols. oleyl alcohol,polyoxyethylene glycol alkyl ethers, octaethylene glycol monododecylether, pentaethylene glycol monododecyl ether, polyoxypropylene glycolalkyl ethers, glucoside alkyl ethers, polyoxyethylene glycol octylphenolethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkylesters, polyoxyethylene glycol sorbitan alkyl esters, sorbitan alkylesters, cocamide MEA, cocamide DEA, dodecyldimethylamine oxide,polyethoxylated tallow amine, and block copolymers of polyethyleneglycol and polypropylene glycol. For example, suitable surfactantsinclude Surfynol 61, commercially available from Air Products andChemicals, Inc. (Allentown, PA).

In certain embodiments, the gypsum slurry (or one or more layersthereof) includes a hydrophobic additive. For example, the gypsum slurryor layer(s) may include wax, wax emulsions and co-emulsions, silicone,siloxane, silanes, or any combination thereof.

In certain embodiments, the first gypsum slurry includes, alternativelyto or in addition to the surfactant, an aqueous polymer or inorganicbinder to enhance penetration of the slurry into the mat. In certainembodiments, the first gypsum slurry includes the binder in an amounteffective to provide from about 0.5 lb/1000 ft² to about 50 lb/1000 ft²binder in the set gypsum layer. In one embodiment, the first gypsumslurry includes the binder in an amount effective to provide from about0.5 lb/1000 ft² to about 15 lb/1000 ft² binder in the set gypsum layer.For example, the binder may be a suitable latex binder, such as ahydrophobic modified acrylic latex binder. In one embodiment, the latexbinder is one with low surface tension, such as ENCOR 300, commerciallyavailable from Arkema (France). For example, the binder may bestyrene-butadiene-rubber (SBR), styrene-butadiene-styrene (SBS),ethylene-vinyl-chloride (EVCl), poly-vinylidene-chloride (PVdCl) andpoly(vinylidene) copolymers, modified poly-vinyl-chloride (PVC),poly-vinyl-alcohol (PVOH), ethylene-vinyl-acetate (EVA),poly-vinyl-acetate (PVA) and polymers and copolymers containing units ofacrylic acid, methacrylic acid, their esters and derivatives thereof(acrylic-type polymers), such as styrene-acrylate copolymers. In oneembodiment, the binder is a hydrophobic, UV resistant polymer latexadhesive. For example, the hydrophobic, UV resistant polymer latexbinder adhesive may be based on a (meth)acrylate polymer latex, whereinthe (meth)acrylate polymer is a lower alkyl ester, such as a methyl,ethyl or butyl ester, of acrylic and/or methacrylic acids, andcopolymers of such esters with minor amounts of other ethylenicallyunsaturated copolymerizable monomers (such as stryrene) which are knownto the art to be suitable in the preparation of UV resistant(meth)acrylic polymer latexes. In certain embodiments, the bindercoating is free of filler.

In certain embodiments, the gypsum slurry (or one or more layersthereof) is substantially free of foam, honeycomb, excess water, andmicelle formations. As used herein, the term “substantially free” refersto the slurry containing lower than an amount of these materials thatwould materially affect the performance of the panel. That is, thesematerials are not present in the slurry in an amount that would resultin the formation of pathways for liquid water in the glass mat of a setpanel, when under pressure.

In certain embodiments, alternatively to or in addition to the matpenetration enhancing gypsum layers discussed herein, the methodsinclude depositing an aqueous polymer or inorganic binder coating ontothe first (internal) surface of the first fiberglass mat, prior todepositing the gypsum slurry onto the first surface of the firstfiberglass mat. For example, the binder coating may include the bindermaterials discussed above with reference to gypsum layer additives. Incertain embodiments, the binder is a latex binder that is free offiller. In certain embodiments, the internal mat coating comprises awetting agent in an amount effective to bring a wet surface tension ofthe coating to 60 dyne/cm or less. In some embodiments, the internalcoating comprises a wetting agent in an amount effective to bring a wetsurface tension of the coating to from about 40 dyne/cm to about 60dyne/cm. For example, the wetting agent may be a surfactant having aboiling point of 200° C. or lower, as discussed above with reference togypsum layer wetting agents. In certain embodiments, the surfactant ispresent in the aqueous coating composition for the internal mat surfacein an amount of about 0.01 percent to about 0.5 percent, by weight. Insome embodiments, the surfactant is present in the aqueous coating in anamount of about 0.05 percent to about 0.2 percent, by weight. In oneembodiment, a binder that is a higher surface tension latex, such asNEOCAR 820, commercially available from Arkema (France), is combinedwith a surfactant, such as Surfynol 440, commercially available from AirProducts and Chemicals, Inc. (Allentown, PA), to provide the desired lowsurface tension.

In certain embodiments, depositing the internal mat aqueous bindercoating includes spraying, curtain coating, rolling, or brushing thecoating onto the first surface of the first fiberglass mat. In certainembodiments, the binder is deposited onto a fibrous surface of thefiberglass mat by a roll coater, knife coater, curtain coater, wire-rodcoater, spraying, or combinations thereof. In some embodiments, themethod includes vacuuming excess aqueous binder from the firstfiberglass mat after depositing the aqueous binder coating thereon. Incertain embodiments, the method includes curing the binder coating priorto depositing the gypsum slurry onto the first surface of the firstfiberglass mat. In certain embodiments, the aqueous binder coating isdeposited onto the first surface of the first fiberglass mat in anamount of from about 5 g/ft² to about 10 g/ft², for example in an amountof about 7.7 g/ft², on a dry basis. In certain embodiments, the aqueousbinder coating is deposited onto the first surface of the firstfiberglass mat in an amount of from about 0.2 g/ft² to about 5 g/ft², ona dry basis.

In some embodiments, the gypsum core includes at least three gypsumlayers, with the outermost gypsum layers of the gypsum core (i.e., thelayers that form an interface with the fiberglass mats). In certainembodiments, both outermost layers are chemically altered for enhancedpenetration.

In some embodiments, the method also includes mechanically vibrating atleast the first fiberglass mat having the first gypsum slurry depositedthereon to effect penetration of the gypsum slurry into the remainingfibrous portion of the first fiberglass mat. In certain embodiments, themethod includes passing at least the first fiberglass mat having thefirst gypsum slurry deposited thereon over a vibration table. Forexample, a fiberglass mat having only one layer of gypsum slurrydeposited thereon (such as the slate coat), or a fiberglass mat havingmultiple gypsum slurry layers, and optionally a second fiberglass matopposite the first fiberglass mat, may be passed over a vibration table.In certain embodiments, the first fiberglass may and gypsum slurry arepassed over the vibration table prior to the panel being passed througha forming plate. In certain embodiments, the vibration table includes atleast one vibrating plate configured to display a mean vibration of fromabout 5 in/s to about 10 in/s. In certain embodiments, the vibrationtable includes at least one vibrating plate configured to vibrate at afrequency of from about 32 Hz to about 20 kHz. In some embodiments, thefiberglass mat and gypsum are passed over two sequential vibratingplates. It has been found that compared to traditional rolls having nubsthereon, the vibration tables achieve superior gypsum slurry penetrationof the fiberglass mat.

In certain embodiments, the panel core slurry (or layers thereof) may bedeposited on the non-coated side of a horizontally oriented moving webof pre-coated fibrous mat. A second coated or uncoated fibrous mat maybe deposited onto the surface of the panel core slurry opposite thefirst coated fibrous mat, e.g., a non-coated surface of the secondcoated fibrous mat contacts the panel core slurry. In some embodiments,a moving web of a pre-coated or uncoated nonwoven fibrous mat may beplaced on the upper free surface of the aqueous panel core slurry. Thus,the panel core material may be sandwiched between two fibrous mats, oneor both having a barrier coating. In certain embodiments, allowing thepanel core material and/or continuous barrier coating to set includescuring, drying, such as in an oven or by another suitable dryingmechanism, or allowing the material(s) to set at room temperature (i.e.,to self-harden).

Gypsum panels disclosed herein advantageously display improved surfacewater resistance and weathering performance.

Methods of constructing a building sheathing system, as shown in FIG. 4, are also provided herein, including installing at least two gypsumpanels 300 having an interface therebetween, and applying a seamingcomponent 320 at the interface between the at least two of the gypsumpanels 300. Gypsum panels used in these methods may have any of thefeatures, properties, or combinations of features and/or properties,described herein. Sheathing systems constructed by these methods mayhave any of the features, properties, or combinations or features and/orproperties, described herein. The seaming component may be any suitableseaming component as described herein.

EXAMPLES

Embodiments of the water-resistive panels disclosed herein wereconstructed and tested, as described below.

Various thin film coatings as described above were produced and appliedto gypsum boards as water barriers. These coatings were found to blockwater penetration under a hydrostatic pressure and pass stringent labtests.

Spray Coating Example

First, the feasibility of industrial hydraulic spray products to applylatex on back of gypsum panel as thin layer topcoat to pass backhydrostatic head test (HHT), according to a test method in accordancewith AATCC 127-2008 and/or AC 212, was evaluated. In particular, a sprayapplication test of 6 coating chemistries was conducted. Overall,results supported proof of concept that the thin layer coatings providea technical solution to pass back HHT.

Table 1 shows the six coating chemistries that were tested while Table 2lists additional properties of those coatings. Generally, the chemistryof the coatings was hydrophobic acrylic latex/optional limestoneslurry/water/blue dye (for visual observation purposes).

TABLE 1 Six Chemistries Tested Generic GP Chemical Generic SDS ReferenceName References Formulas Quantity Chemical 1 SW41-1 SW41-1 Snap720/H2O/Blue 2-5 Coating Dye = 100/30/0.10 gallons Chemical 2 SW41-2SW41-2 Snap 728/H2O/Blue 2-5 Coating Dye = 100/30/0.10 gallons Chemical3 SW41-3 SW41-3 Neocar820/H2O/Blue 2-5 Coating Dye = 100/30/0.010gallons Chemical 4 SW41-4 SW41-1/ Snap720/C35/H2O/Blue 2-5 CoatingLimestone Dye = 50/50/30/0.10 gallons Slurry Chemical 5 SW41-4 SW41-2/Snap 728/C35/H2O/Blue 2-5 Coating Limestone Dye = 50/50/30/0.10 gallonsSlurry Chemical 6 SW41-6 SW41-3/ Neocar820/C35/H2O/Blue 2-5 CoatingLimestone Dye = 50/50/30/0.010 gallons Slurry

TABLE 2 Additional Chemical Properties of Coatings Tested ViscosityApplication Trial Line Range Particle Range Speed Chemistry (cps) pHSize (g/sf) (fpm) SW41-1 80 6.5 to 9.0 0.07 2 to 6 125 to 150 CoatingSW41-2 80 6.5 to 9.0 0.08 2 to 6 125 to 150 Coating SW41-3 80 6.5 to 9.00.1 2 to 6 125 to 150 Coating SW41-4 800 6.5 to 9.0 3.2  4 to 11 125 to150 Coating SW41-4 800 6.5 to 9.0 3.2  4 to 11 125 to 150 Coating SW41-6800 6.5 to 9.0 3.2  4 to 11 125 to 150 Coating

The coatings were applied to ¼ inch DensDeck Prime (Georgia-Pacific)gypsum roof board using an electric hydraulic spray gun (flat nozzles,TPU tip 8002, 8003), 42 psi, 100% duty cycle in an 8 to 12-inch widthspray pattern. Boards were coated at the ˜10 to 20 lbs/msf applicationrate at one and two coating passes down the moving conveyer at ˜175 fpm,onto dry and damp moist boards. Application of coating onto damp boardswas observed to provide a more fluid/even coating (intended to mimicactual line conditions for applying the coating before the knife on thegypsum board line, i.e., prior to gypsum slurry drying).

Next, the coated samples were tested for HHT passage, according to atest method in accordance with AATCC 127-2008 and AC 212. A hydrostatichead test assembly is illustrated in FIGS. 5A and 5B. The coated sampleswere also tested for water weight gain and water column loss, accordingto a test method in accordance with AATCC 127-2008 and AC 212. Theresults are shown in Table 3 below and in FIGS. 6 and 7 .

TABLE 3 Test Results Coating Wt. Wt. H2O Comments on ¼″ lbs/ Gain Gainloss Pass/ on failure Back DDP msf (g) (%) (in.) Fail modes Control (Hboard, 17.27 1.16% 10.33 Fail (6 of 6) side and surface 072616 Antioch)channeling Chem#1: SW41-1- Board# 2-coat/damp-6, -16 14.33 4.14 0.32%0.00 Pass (6 of 6) no channeling 1-coat/damp, -21, 22 11.85 7.87 0.53%0.00 Pass (6 of 6) no channeling 2-coat/dry, -8, -10 15.70 9.4 0.63%0.13 Pass (3 of 6) slight side and surface channeling 1-coat/dry, 20,-23 11.57 7.87 0.86% 1.29 Pass (2 of 6) slight side and surfacechanneling Chem#2: SW41-2- Board# 2-coat/damp-2, -4 14.33 4.36 0.29%0.00 Pass (5 of 6) little side and surface channeling 1-coat/damp, -13,15 9.65 7.92 0.52% 0.19 Pass (4 of 6) slight side and surface channeling2-coat/dry, -12, -14 15.43 9.33 0.62% 0.23 Pass (2 of 6) slight side andsurface channeling 1-coat/dry, 17, -19 10.75 13.04 0.86% 1.46 Fail (6 of6) spotty coating, channeling Chem#3: SW41-3- Board# 2-coat/damp-1, -1815.15 5.72 0.38% 0.08 Pass (4 of 6) slight side and surface channeling1-coat/damp, -9, 11 10.74 7.39 0.49% 0.00 Pass (6 of 6) no channeling2-coat/dry, -3, -24 14.33 10.63 0.70% 1.90 Pass (2 of 6) side andsurface channeling 1-coat/dry, 5, -7 10.47 12.68 0.83% 0.58 Pass (2 of6) slight side and surface channeling Chem#4: SW41-4- Board#2-coat/damp-31, -32 21.94 4.69 0.30% 0.00 Pass (6 of 6) no channeling1-coat/damp, -36, 37 18.45 6.43 0.40% 0.00 Pass (6 of 6) no channeling2-coat/dry, -28, -29, 19.65 5.00 0.30% 0.00 Pass (8 of 9) little sideand surface -30 channeling 1-coat/dry, 39, 40 15.43 14.25 1.00% 1.75Fail (6 of 6) spotty coating, channeling Chem#5: SW41-5- Board#2-coat/damp-49, -51 19.57 5.84 0.39% 0.00 Pass (6 of 6) no channeling1-coat/damp, -44, 45 15.43 5.50 0.37% 0.00 Pass (6 of 6) no channeling2-coat/dry, -46, -47, 15.87 7.67 0.51% 0.01 Pass (11/12) slight side andsurface -48, -50 channeling 1-coat/dry, 42, -43 14.99 17.45 1.58% 0.19Fail (6 of 6) spotty coating, channeling Chem#6: SW41-6- Board#2-coat/damp-54, -55 21.77 4.65 0.31% 0.00 Pass (6 of 6) no channeling1-coat/damp, -58, 59 11.02 9.69 0.64% 0.04 Pass (4 of 6) slight side andsurface channeling 2-coat/dry, -52, -53 20.67 10.39 0.70% 0.19 Fail (6of 6) slight side and surface channeling 1-coat/dry, 56, -57 10.20 15.391.03% 3.38 Fail (6 of 6) slight side and surface channeling

Overall, it was found that the damp coated boards passed the HHT test ata rate of greater than 90%. Additionally, a water column loss of 0″ wasobserved in 34 out of 36 samples.

Photographs of uncoated and coated boards are provided in FIGS. 8 and 9, respectively. As can be seen, the uncoated product contains moremicro-pores than the coated board. The coating acts as level agentfilling in the voids of the glass mat and seals the micro-pores.

Thus, it was determined that it is technically feasible to achieve (byspraying in this example) a thin layer coating that provides improvedwater resistance.

Direct Roll Coating Example

Direct roll coating (DRC) trials were also conducted in which acryliclatex coating materials (Snap 720, Snap 728 and Neocar 820) were appliedto the back of standard DensDeck® Prime gypsum boards (½″ and ¼″) at atarget line speed of 80fpm. For these samples, a 1:1 weight ratio oflatex/CaCO3 slurry were manually mixed. The coating viscosity was in therange of 700 to 1000 centipoises.

Four trial conditions on DRC were conducted, as outlined in Table 4below. Two paints were applied on DRC line on the back of ½″. For trialconditions 2 and 4, a secondary layer coat on the top of the first layerat 90 ft/min without any peeling off issue. Coatings were observed to beclear and translucent, does not hide on-line manufacturing board lineink print on the DRC line. Wet paints were observed to be fully driedout on the DRC line. Freshly dried coated boards were normally stackedwithout any blocking issues. Risers did not stick to the freshly driedcoated surfaces.

TABLE 4 Trial Conditions for DRC Tests Conditions Total 1^(st) 1^(st) &(Spray Usage Application Application DRC 2^(nd) 2^(nd) DRC Paint RateRate (g/sf) Rate (g/sf) Speed IR & Color) Coating (lbs/msf) 1st DRC 2ndDRC (fpm) Oven 3^(rd) IR Control No coating 0 NA NA NA NA NA Trial 1ANeocar 13.2 6 0 90 on on (Blue) 820/CaCO3 slurry (1:1) Trial 2B Neocar19.42 5.5 3.35 90 on on (black) 820/CaCO3 slurry (1:1) Trial 3Snap720/slurry 11.56 5.25 0 90 on on (orange) CaCO3 (1:1) Trial 4Snap720/slurry 16.85 3.3 4.35 90 on on (yellow) CaCO3 (1:1)

A 24-Hour blocking evaluation was also conducted on these samples, inwhich after the 24 period, boards were examined by sorting. Overall,risers did not stick to the surfaces of coated boards. For allconditions during the hand handling evaluation, the topcoat layers werenot observed to be tacky. There was no visual evidence of face coatingseparating to the back of the board.

HHT, nail pull, flexural, and other performance test results for thesesamples are shown in Table 5 below.

TABLE 5 Testing Results Summary Table DRC Face/ Ave. WVTRs 2-Hr BackBack ′1 perm = 1 Nail MD-FU MD-FD CU-FU CD-FD Back 2-HR HumidifiedThickness HHT grain/(ft2 hr Pull Flexural Flexural Flexural FlexuralCobbs TWA Deflection Coating (lbs/msf) Test inHg) (lbf) (lbf) (lbf)(lbf) (lbf) (grams) (%) (lbf) No 0 Fail 22 96 139 146 167 150 0.7 5.426/20 coating/ (12/12) Control Neocar 13.2 Pass 8 90 141 146 228 182 0.63.5 20/20 820/CaCO3 (11/12) (1:1) Neocar 19.4 Pass 9 95 160 146 233 1720.7 3.9 21/20 820/CaCO3 (11/12) (1:1) Snap720/ 11.56 Pass 17 103 163 134218 181 0.7 3.2 19/21 CaCO3 (11/12) (1:1) Snap720/ 16.85 Pass 12 99 170149 219 176 0.7 3.5 21/21 CaCO3 (11/12) (1:1)

Overall, the Examples demonstrate that a water-resistant barrier forgypsum panels can be obtained by spraying and rolling a very thin layerof the substantially continuous barrier coatings described herein. Thecoatings show good comprehensive properties, including faster drying,moisture & water-resistance, thermal stability, outstanding blockresistance, adhesion and durability. Moreover, the tested panelsdisplayed significantly improved back HHT passing rate (90%),significantly improved column water loss (˜20×, reduced from >5 in lossto <0.25 in loss), and significantly improved % water gain (Reduced from−4% to <0.5%).

Indeed, improvements in total water absorption, Cobbs (face and back)and sole face HHT were observed in the tested panels. Over 15 latexcoatings (acrylic, UV-cure, polyurethane, PVB, EVA, SBR, AS) wereevaluated, with acrylic based latex coatings, such as Snap 720, Snap 728and Neocar 820 found to provide outstanding water-resistance, superiorblock resistance, and allow to quickly dry out to form tough and clearfilm at 5-20 lbs/msf of lower applied raw material usage rate.

Thus, the gypsum sheathing panels and building sheathing systemsdisclosed herein display water-resistive air barrier properties thatwere previously achieved in gypsum panels only through attachingseparate water-resistive air barriers (e.g., mechanically attachedflexible sheet, self-adhered sheets, fluid-applied membranes, sprayfoams) thereto. Because gypsum panels display fire resistanceproperties, these panels and systems provide advantages over wood-based(e.g., oriented strand board) panels.

In these gypsum panels and sheathing systems, air pockets, voids, or pinholes in the surface of the panel may be substantially eliminated, sothat the panels display the desired water resistive barrier and airbarrier properties independent of externally applied barrier products.These improved sheathing panels may be combined with seaming components(i.e., components that treat the joints, or seams, between panels) togreatly reduce the cost, time, and complexity of installation of awater-resistive air barrier that provides the desired resistance to bulkwater without affecting the water vapor transmission rate of the panel.Accordingly, the disclosed system advantageously eliminates the need forapplying further materials to a gypsum panel (e.g., either a membrane orliquid/foam material) to achieve water-resistive air barrier properties,when the seams are treated, and also provides fire resistance.

While the disclosure has been described with reference to a number ofembodiments, it will be understood by those skilled in the art that theinvention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions, or equivalent arrangements not describedherein, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A gypsum panel, comprising: a set gypsum coreassociated with a first surface of a first fiberglass mat; and asubstantially continuous barrier coating comprising a polymer binderapplied to a second surface, opposite the first surface, of the firstfiberglass mat, in an amount of from about 1 lb/MSF to about 40 lb/MSF,such that the substantially continuous barrier coating has an averagethickness atop the second surface of from about 1 micron to about 100microns, wherein the substantially continuous barrier coatingsubstantially eliminates pin holes present in the exposed second surfaceof the first fiberglass mat.
 2. The gypsum panel of claim 1, wherein thesubstantially continuous barrier coating is applied to the secondsurface of the first fiberglass mat in an amount of from about 1 lb/MSFto about 25 lb/MSF.
 3. The gypsum panel of claim 1, wherein thesubstantially continuous barrier coating is applied to the secondsurface of the first fiberglass mat in an amount of from about 10 lb/MSFto about 15 lb/MSF.
 4. The gypsum panel of claim 1, wherein thesubstantially continuous barrier coating has an average thickness offrom about 1 micron to about 50 microns.
 5. The gypsum panel of claim 1,wherein the polymer binder comprises a polymeric emulsion or resinselected from acrylics, siloxane, silicone, styrene-butadienecopolymers, polyethylene-vinyl acetate, polyvinyl alcohol, polyvinylchloride (PVC), polyurethane, urea-formaldehyde resin, phenolics resin,polyvinyl butyryl, styrene-acrylic copolymers, styrene-vinyl-acryliccopolymers, styrene-maleic anhydride copolymers, and alkyd emulsions. 6.The gypsum panel of claim 1, wherein the polymer binder comprises anultra-small particle size or structured nano acrylic latex or apolystyrene-acrylic copolymer latex.
 7. The gypsum panel of claim 1,wherein the polymer binder is hydrophobic.
 8. The gypsum panel of claim1, wherein the polymer binder comprises a UV curable monomer or polymerselected from epoxy acrylate, urethane acrylate, and polyester acrylate.9. The gypsum panel of claim 1, wherein the substantially continuousbarrier coating contains the polymer binder in an amount of from about 5percent to about 75 percent, by weight, on a dry basis.
 10. The gypsumpanel of claim 1, wherein the substantially continuous barrier coatingfurther comprises an inorganic filler.
 11. The gypsum panel of claim 10,wherein the substantially continuous barrier coating contains thepolymer binder in an amount of from about 35 percent to about 65percent, by weight, and the inorganic filler in an amount of from about35 percent to about 65 percent, by weight, measured on a dry basis. 12.The gypsum panel of claim 11, wherein the polymer binder and theinorganic filler are present in amounts of within 5 percent, by weight,of each other.
 13. The gypsum panel of claim 1, wherein the gypsum paneldisplays an HET passing rate of at least 90 percent.
 14. The gypsumpanel of claim 1, wherein the gypsum panel displays a column water lossof less than 0.25 inch.
 15. The gypsum panel of claim 1, wherein thegypsum panel displays a water gain of less than 5 percent.
 16. A gypsumpanel, comprising: a set gypsum core associated with a first surface ofa first fiberglass mat; and a substantially continuous barrier coatingcomprising a polymer binder applied to a second surface, opposite thefirst surface, of the first fiberglass mat, in an amount of from about 1lb/MSF to about 40 lb/MSF, such that the substantially continuousbarrier coating has an average thickness of from about 1 micron to about100 microns, wherein: the substantially continuous barrier coatingeliminates at least 99 percent of pin holes present in the exposedsecond surface of the first fiberglass mat; and the polymer bindercomprises a UV curable monomer or polymer selected from epoxy acrylate,urethane acrylate, and polyester acrylate.
 17. The gypsum panel of claim16, wherein the substantially continuous barrier coating is applied tothe second surface of the first fiberglass mat in an amount of fromabout 1 lb/MSF to about 25 lb/MSF.
 18. The gypsum panel of claim 16,wherein the substantially continuous barrier coating has an averagethickness of from about 1 micron to about 50 microns.
 19. The gypsumpanel of claim 16, wherein the substantially continuous barrier coatingcontains the polymer binder in an amount of from about 5 percent toabout 75 percent, by weight, on a dry basis.
 20. The gypsum panel ofclaim 16, wherein the substantially continuous barrier coating furthercomprises an inorganic filler.